Arc extinguishing attachment for air-break switches



Oct. 23, 1951 T. F. JOHNSON 2,572,525

ARC EXTINGUISHING ATTACHMENT FOR AIRBREAK SWITCHES Filed March 23, .19502 smu -5mm 1 INVENTOR Z'E domvsolv ATTORNEYS Oct. 23, 1951 T. F. JOHNSONA RC EXTINGUISHING ATTACHMENT FOR AIR-BREAK SWITCHES 2 SHEETS-SHEET 2Filed March 23, 1950 INVENTOR It yo'mvsmv BY. Z a ,,M

ATTORNEYS Patented Oct. 23, 1951 ARC EXTINGUISHING ATTACHMENTFORAIR-BREAK SWITCHES Tomlinson F. Johnson, Atlanta, Ga.

Application March 23, 1950,.Serial No. 151,388.

This invention relates to high tensionswitches or. circuit interruptershaving provision for ex.- tinguishing the are under heavy loads whentheswitches are operated to isolate portions of a line. Amongotherrobjects, the invention aims to providea simplified and effectiveare extinguishing or. interrupter attachment for useon group operatedair-break switches, whereby theswitches maybe employed.for disconnectingor isolati sections ofhcavy voltage lines operating .-under full loads.

Another aim ofthe invention is ..to providev a simplified and. effectivearc. extinguisher :or. inter? rupter device, adapted to beappliedtoordinary air-break: switches having vertically -tiltable. or swingingblades and equipped with arcing horns.

Other aims and advantages of the invention will appear in thespecification when .considered in connection with the accompanyingdrawings, wherein:

Fig. 1 is a side elevation of a single switch having the preferred formofsattachment applied thereto;

Fig. 2 is a fragmentary .view, similar to. Fig. 1, showing the switch.in its partially opened .posie tion;

Fig. 3 is a fragmentary top. plan view of the arc extinguishingattachment shown in Fig. 1;

Fig. 4is .a fragmentary vertical sectional .view of the attachment;

Fig. 5 is a sectional view taken on the. line 5-:5 of Fig. 4; and

Fig. 6 is a sectional view taken on the-line 66 of Fig. 4.

Group operated air-break switches ofthe type disclosed are employed fordisconnecting and isolating sections of high voltage transmission lines.Unless they are provided with special load breaking attachments, suchswitches cannot be operated under full load conditions. They can breakonly limited transformer charging currents and will be severely damaged,due to arcing, under full loads. It is, therefore, a principal object'ofthe present invention to provide a simipliiied and very effective areextinguishing attachmentfor high tension, air-break switches, which willenable them to be operated under load conditionsywith out damage to theswitch contacts.

Referring more particularly to the drawings,

6 Claims. (Cl. 209-146) horns 16 made of heavy wire, such as siliconbronze.

The stationary contact is of the usual typeand includes a -bracket I!having a base plate [8 to which: the conductor I9 is connected. Inaccordance with I this invention, a supporting bracket plate 20 issecured to the base plate 18: and has upstanding ears 2| for carryingthe arcing attachment. A horizontal shelf member 22 has avertical arm 23secured to the upstanding ears 2| bya pair of bolts 24. This shelf alsohas anintegral upstanding ear to whichan inverted,' U-.shaped arc horn26 is connected by a clamping plate 2? and bolts 28. The movablearcingliorns [5 are adapted to straddle thestationary arcinghorns in theusual manner.

The outer end portion ofthe shelf is provided with a trough-shapedsupporting member 29 having-an upstanding flange 30 at its front endsides, so thatwater will drain out of it and cannot-accumulate andfreeze in it. An upstanding arcing, conductor-rod 3| isscrewthreadedinto a vertical opening in the trough-shaped member. Aninterru ter tube 32, preferably made of hard, fibrous insulatingmaterial, i supported for slidingmoyementon thearcingconductor rod 3|-by means of a hub-shaped guide. member 33, made of alumihumorother'light weight material, It loosely engages thelower endof therodand has a cylindricaliiange Stoonnectedto thelower end of the tubebymeans of apair of diametrically opposite arms 35,. the arrangement beingsuch thatthehub member does not close the lower end of the tube andrests on thebottom ofthetroughshapedmemberii). An aluminumcylinder orskirt-3B surrounds the guidemember 33 andex; tends to, a point near thebottom efthe trough}? to direct-the gas'into the troughf Thecylindricalsleeve and flan e 3-; of the hub-shaped guide member are shown as beingconnected t0; the lower end of the tubeby screws 31. Thgupper end of thetube isshownashavinga re novable bronze plug member 38; inserted thereinwith asvaeat a pair of radial lugs 39 engaging radial notches in the endof the tube. It is held in place by a cap 40 telescoped over and securedto the upper end of the tube by screws 4|. The cap is shown as having aplurality of cam shaped ribs :22 adapted to guide the wires of thearcing horns l6 downwardly over the cap to engage their lower edges 43,so that, when the switch is opened, the horns will lift the tube. Thelower portions of the cam shaped ribs are shown as being rounded at M toact as guiding cams, so that the wires of the horn 56 will spread apartand be disengaged from the cap in case the tube is stuck on the arcingrod 31 during its lifting movement. A short conductor rod 45 is shown asbeing threaded through an upstanding boss M on the cap member 39 andthrough the upper end portion of the plug 38 so that its lower endcontacts the upper end of the arcing rod 3|. It is held in its adjustedposition by a jamb nut 41 and extends only a short distance above theupper end of the cap. This rod also serves as a guide for the movablearcing horns it when the switch is being closed.

As will be seen in Fig, 1, the lower ends or shoulders of the cap member39 are above the level of the upper end of the stationary U-shaped horn26, so that the movable arcing horns IE will engage the bottom of thecap during the opening movement of the switch blade to re-establish thecircuit through the interrupter and lift the tube as the blade swingsopen. As soon as the tube is lifted, the arc will be transferred to thetube between the contact member 38 and the upper end of the arcing rod.When this occurs, the arc will melt a minute portion of the contact rod45 and gasefy it, due to the intense heat. This will create an upwardpressure in the tube which will assist the moving horns IS in raisingthe interrupter tube to the top of its stroke and thus rupture the areby very rapid attenuation. When the lower end of the contact rod 55 isburned off, it can easily be re-adjusted to make good contact with theupper end of the arcing rod 3|.

The arc drawn in the tube is ruptured or extinguished before the tubereaches the upper limit of its stroke. The stroke is shown as beinglimited by means of an annular stop collar 48 adjustably mounted on thearcing rod 3:, so that the hub-shaped guide member 33 strikes it as thetube is lifted by the movable arcing horns l6 and the free ends of thehorns slide out of engagement with the cap during the final openingmovement of the blade. The hot gas or flame is discharged downwardlyfrom the tube into the troughshaped member 29, and the flange 30prevents it from damaging the stationary contact. Thus, thetrough-shaped member serves the dual purpose of supporting the tube andacting as a shield for protecting the stationary contact of the switch.

When the arc is extinguished, the tube will fall by gravity to there-set position, shown in Fig. 5. During the closing movement of theswitch, the fork-shaped arcing horns [6 will straddle the upstanding,contact rod 45 and will be guided over the top of the cap by thecam-shaped ribs 42 to straddle the stationary U-shaped horn 26.Incidentally, the width of the U-shaped horn corresponds with thediameter of the tube 32, so that the forks of the arcing horns IE willreadily engage the shoulders 43 at the bottom of the cap when the switchis open and the forks are disengaged from the stationary horn.

From the foregoing description, it will be seen that the arcextinguishing attachment is very simple in its construction andoperation. It is 4 so designed that it can be applied to airbreakswitches of diiferent types and has proved to be effective in breakingheavily loaded circuits without damage to the switch.

Obviously, the invention is not restricted to the particular embodimentthereof herein shown and described, but is capable of variousmodifications within the scope of the appended claims.

What is claimed is:

1. An arc extinguishing attachment for an airbreak switch having avertically swinging blade and a pair of parallel arcing horns,comprising a vertically movable interrupter tube of insulating materialmounted on the stationary contact and having a metal cap member at itsupper end; and a stationary arcing conductor rod electrically connectedto the stationary switch contact and supported within the tube with itsupper end normally in contact with said metal cap; the movable arcinghorns being engageable with said cap as the switch blade is raised toits open position to lift the tube and start an are between the cap andth arcing conductor rod, whereby gas pressure created by the arc willforce the tube upwardly to elongate and extinguish the arc.

2. An arc extinguishing attachment for an airbreak switch, as set forthin claim 1, wherein the arcing conductor rod and movable tube aremounted on a bracket secured to the stationary switch contact; and ahub-shaped guide member slidably mounted on the arcing conductor rodconnected to the bottom of the tube to confine the tube to movevertically on the rod; and a stop member on the rod coacting with saidguide member to limit the upward movement of the tube.

3. An arc extinguishing attachment for an airbreak switch, as set forthin claim 1, wherein the arcing conductor rod and movable tube aresupported on a bracket secured to the stationary switch contact; avertical, inverted, U-shaped arcing horn parallel with and adjacent tosaid tube terminating slightly below the cap on said tube and poistionedto be straddled by the arcing horns on the switch blade, whereby thecurrent flow is established through the tube cap and arcing conductorrod as the movable arcing horns are swung above the U-shaped horn; meansto guide the tube to slide upwardly on the conductor rod; and means tolimit the upward movement of the tube.

4. An arc extinguishing attachment for an airbreak switch, as set forthin claim 1, wherein the cap on said tube has a plurality of verticalribs to act as spreading cams for the horns; and said ribs havingshoulders at their bottom edges to be engaged by the movable arcinghorns.

5. An arc extinguishing attachment for an airbreak switch having avertically swinging blade and a pair of parallel arcing horns,comprising a vertically movable interrupter tube of insulating materialmounted on the stationary contact and having a metal cap member at itsupper end; a stationary arcing conductor rod electrically connected tothe stationary switch contact and supported within the tube with itsupper end normally in contact with said metal cap; the movable arcinghorns being engageable with said cap as the switch blade is raised toits open position to lift the tube and start an are between the cap andthe arcing conductor rod, whereby gas pressure created by the arc willforce the tube upwardly to elongate and extinguish the arc; verticalcam-shaped ribs on the cap acting as spreading cams for the horns; saidribs having shoulders at their bottom edges to be engaged by the movablearcing horns; a vertical, inverted, U- shaped horn spaced from the tubewith its upper end terminating short of the cap on the tube; and a shortconductor rod extending through and adjustably connected to the cap incontact with the upper end of said arcing conductor rod.

6. An arc extinguishing attachment for an airbreak switch, as set forthin claim 1, wherein the arcing conductor rod and movable tube aresupported on a horizontal trough-shaped member with the lower, open endof the tube above the bottom of said trough-shaped member, saidTOMLINSON F. JOHNSON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Name Date Pittman et a1 Nov. 9, 1937 Number

